Does anyone know if UE/Ofna 8-Spider diffs will fit in mike's V3 cases?

I was thinking about trying the 8-spider diffs or a set of Torsen diffs. I'm reluctant though because for my use I don't think $200 worth of diffs will be worth it. I'm just a little too obsessed with upgrading my gear!

Still waiting to see if Mike has anything to say about the diff wobble. Might go ahead and order some Ofna or Mugen diff cups and see if that fixes the issue. Otherwise there are Hyper ST Pro diffs on Ebay for about $16 each, and they have the same slightly spiral cut gears like the V3's. The diff pinions that came with the V3 kits would most likely work fine with them. The Hyper ST ring gears seal with an O-ring instead of a paper gasket if that makes any difference?

What do you guys think, try just getting new diff cups, or go for the complete diffs? Or wait a bit more and see if we find an easier fix?

I thought generally truggy gear ratio is 43/10 and buggy gear ratio is 43/13. Both use a 43 tooth ring gear so they would be the same size. You would re-use the 13T diff pinion from the V3 kit because they both have the same spiral cut, just a tiny bit of spiraling. Overall ratio would stay 43/13.

I am drawing up some custom diff cups for the caster racing differential that I will machine for myself if no other fix comes up. Aluminum diff cup with titanium inserts.. Being a machinist has its advantages sometimes!

Mike's RCM hybrid cases only fit the smaller diffs, like; Mugen, Kyosho, Associated, and Losi...UE/Ofna diffs will not fit, though I wish they would, because the UE/Ofna 8-spider diffs are my favorite of all time and I have 7 of them (3 of them center-diffs), but they are too big.

Appetite, titanium wouldn't be the best insert material for the output shafts to ride on, because even though Ti is very hard, is has a high friction coefficient...brass is the best choice for that application, with 304 stainless-steel being second.

are you all cross tighting? or going in a line...i assemble mine like mounting a tire...making sure all sides are tightened all the same.

Yeah I do cross tightening also, so everything is as even as possible. After about 25 times of trying to assemble the diffs I actually got them to line up and not wobble. I don't know how I did it, just kept re-trying and trying to be extra careful lining up the holes. Now I'm afraid to take them back apart and fill them with oil, I'll probably never get them assembled right again!

I think if the holes are misaligned by a tiny bit or if the screws are threaded in even a hair off-center then the ring gear won't seat right (possibly caused by the diff cup getting tweaked out of shape by misaligned screws)

Appetite, titanium wouldn't be the best insert material for the output shafts to ride on, because even though Ti is very hard, is has a high friction coefficient...brass is the best choice for that application, with 304 stainless-steel being second.

Thanks for the tip.
The inserts I had in mind was for supporting the pins for the spider gears, not for the output shaft to ride on. I was thinking of making the entire diff cup out of 7075-T6 alu. and only the "spider-pin inserts" out of Ti, so the output shaft will ride on the alu. cup itself. Is this a bad idea?
Maybe a press fit brass sleeve in the bottom of the cup will be better?

Quote:

Originally Posted by neweuser

are you all cross tighting? or going in a line...i assemble mine like mounting a tire...making sure all sides are tightened all the same.

Yes, I too am cross tightening the screws. The problem with my cups is that the surface that mates to the ring gear is not perpendicular to the axis of the metal insert in the bottom of of the cup which the bearing sits on. (probably not proper metrology jargon.. )

Yep, bad idea...you can't let the output shaft ride on the aluminum, even the really hard 7075, that's why you see 99% of the aluminum cups on the market with brass or stainless-steel inserts in the cup. I mean, you can use the 7075 as a wear surface, but it won't take long for slop to develop on that side.

7075 is an awesome choice to make the cup out of, as long as you add a brass or stainless-steel insert for the output shaft to ride on. You don't have to worry about the output shaft on the ring-gear side, because the ring-gear is hardened-steel and makes an excellent wear surface.

The Ti cross-pin idea sounds fine, even though they will have spider gears rotating on them, but the spider gears themselves are soft enough for it not to matter.

Why'd RCM quit making these? Seems like with all the brushless revos these days and guys spending a lot of time/money trying to fit LST diffs in them that they wouldn't have a hard time selling these still.